Methanol electrochemical oxidation

Korzeniewski C, Childers CL. 1998. Formaldehyde yields from methanol electrochemical oxidation on platinum. J Phys Chem B 102 489-492. 

Bergamaski K, Pinheiro ALN, Teixeira-Neto E, Nart EC. 2006. Nanoparticle size effects on methanol electrochemical oxidation on carbon supported platinum catalysts. J Phys Chem B 110 19271-19279. 

A 3-D ordered macroporous carbon loaded with Pt-Ru alloy particles was evaluated for electrochemical performance in a DMFC [248,251], The carbon displayed advantages over Vulcan XC-72 carbon black. Another study also showed that a Pt-Ru catalyst supported on ordered macroporous carbon exhibited higher specific activity for methanol oxidation than the commercial E-TEK catalyst [254], We also demonstrated that the electrochemical properties of Pt catalysts, supported on microporous carbon with an amorphous carbon core/ graphitic carbon shell structure [75,337], on an OMC [135], and on a 3-D macroporous carbon [256] improved the specific activity of methanol electrochemical oxidation at room temperature. 

Platinum-Based Anode Catalysts for Polymer Electrolyte Fuel Cells, Fig. 4 (a) Reaction mechanism for the methanol electrochemical oxidation proposed by Lamy et al. (b) Schematic representation of a DEFC (Reproduced by permission from [16]). (c)... 

Lei, Z., An, L., Dang, L., Zhao, M., Shi, X, Bai, S. Cao, Y Highly dispersed platinum supported on nitrogen-containing ordered mesoporous carbon for methanol electrochemical oxidation. Micropor. Mesopor. Mater. 119 (2009), pp. 30-38. 

Figure 6.55 Proposed methanol electrochemical oxidation pathway at DMFC anode. (Adapted from Ref. [49].)...

Several activities, if successful, would strongly boost the prospects for fuel ceU technology. These include the development of (/) an active electrocatalyst for the direct electrochemical oxidation of methanol (2) improved electrocatalysts for oxygen reduction and (2) a more CO-tolerant electrocatalyst for hydrogen. A comprehensive assessment of the research needs for advancing fuel ceU technologies, conducted in the 1980s, is available (22). 

A viable electrocatalyst operating with minimal polarization for the direct electrochemical oxidation of methanol at low temperature would strongly enhance the competitive position of fuel ceU systems for transportation appHcations. Fuel ceUs that directiy oxidize CH OH would eliminate the need for an external reformer in fuel ceU systems resulting in a less complex, more lightweight system occupying less volume and having lower cost. Improvement in the performance of PFFCs for transportation appHcations, which operate close to ambient temperatures and utilize steam-reformed CH OH, would be a more CO-tolerant anode electrocatalyst. Such an electrocatalyst would reduce the need to pretreat the steam-reformed CH OH to lower the CO content in the anode fuel gas. Platinum—mthenium alloys show encouraging performance for the direct oxidation of methanol. 

J.K. Hong, I.-H. Oh, S.-A. Hong, and W.Y. Lee, Electrochemical Oxidation of Methanol over a Silver Electrode Deposited on Yttria-Stabilized Zirconia Electrolyte, /. Catal. 163, 95-105 (1996). 

The transient response of DMFC is inherently slower and consequently the performance is worse than that of the hydrogen fuel cell, since the electrochemical oxidation kinetics of methanol are inherently slower due to intermediates formed during methanol oxidation [3]. Since the methanol solution should penetrate a diffusion layer toward the anode catalyst layer for oxidation, it is inevitable for the DMFC to experience the hi mass transport resistance. The carbon dioxide produced as the result of the oxidation reaction of methanol could also partly block the narrow flow path to be more difScult for the methanol to diflhise toward the catalyst. All these resistances and limitations can alter the cell characteristics and the power output when the cell is operated under variable load conditions. Especially when the DMFC stack is considered, the fluid dynamics inside the fuel cell stack is more complicated and so the transient stack performance could be more dependent of the variable load conditions. 

The electrochemical oxidation of methanol occurs on the anode electrocatalyst (e.g., dispersed platinum), which constitutes the negative electrode of the cell ... 

The complete electrochemical oxidation of methanol to carbon dioxide. 

In 1965, synergistic (nonadditive) catalytic effects were discovered in elecho-chemical reactions. It was shown in particular that the electrochemical oxidation of methanol on a combined platinum-ruthenium catalyst will occur with rates two to three orders of magnimde higher than at pure platinum even though pure ruthenium is catalytically altogether inactive. 

A period of high research activity in electrocatalysis began after it had been shown in 1963 that fundamentally, an electrochemical oxidation of hydrocarbon fuel can be realized at temperatures below 150°C. This work produced a number of important advances. They include the discovery of synergistic effects in platinum-ruthenium catalysts used for the electrochemical oxidation of methanol. 

Figure 6.21 Suggested reaction scheme for the electrochemical oxidation of methanol on metal electrodes. (After Housmans et al. [2006].)...

Gilman S. 1964. The mechanism of electrochemical oxidation of carbon monoxide and methanol on platinum. II. The reactant-pair mechanism for electrochemical oxidation of carbon monoxide and methanol. J Phys Chem 68 70-80. 

Fuel cells are electrochemical devices transforming the heat of combustion of a fuel (hydrogen, natural gas, methanol, ethanol, hydrocarbons, etc.) directly into electricity. The fuel is electrochemically oxidized at the anode, whereas the oxidant (oxygen from the air) is reduced at the cathode. This process does not follow Carnot s theorem, so that higher energy efficiencies are expected up to 40-50% in electrical energy and 80-85% in total energy (heat production in addition to electricity). 

Bett JS, Kunz HR, Aldykiewicz AJ Jr, Eenton JM, Bailey WS, Me Grath DV. 1998. Platinum-macrocycle co-catalysts for the electrochemical oxidation of methanol. Electrochim Acta 43 3645-3655. 

Chu D, Gilman S. 1996. Methanol electro-oxidation on unsupported Pt-Ru alloys at different temperatures. J Electrochem Soc 143 1685-1690. 

Gasteiger HA, Markovic N, Ross PN, Caims EJ. 1994. Temperature-dependent methanol electro-oxidation on well-characterized FT-Ru alloys. J Electrochem Soc 141 1795-1803. 

Shropshire JA. 1965. The catalysis of the electrochemical oxidation of formaldehyde and methanol by molybdates. J Electrochem Soc 112 465-469. 

Vidal F, Busson B, Tadjeddine A. 2005. Probing electronic and vibrational properties at the electrochemical interface using SFG spectroscopy Methanol electro-oxidation on Pt(llO). Chem Phys Lett 403 324-328. 

Different experimental approaches were applied in the past [6, 45] and in recent years [23, 46] to study the nature of the organic residue. But the results or their interpretation have been contradictory. Even at present, the application of modem analytical techniques and optimized electrochemical instruments have led to different results and all three particles given above, namely HCO, COH and CO, have been recently discussed as possible methanol intermediates [14,15,23,46,47]. We shall present here the results of recent investigations on the electrochemical oxidation of methanol by application of electrochemical thermal desorption mass spectroscopy (ECTDMS) on-line mass spectroscopy, and Fourier Transform IR-reflection-absorption spectroscopy (SNIFTIRS). 

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